것은 아니다

is not necessarily

→ 것
phrase Rare #20,444
is not necessarily Often softens a statement by saying something is not always or not necessarily the case. In other contexts, it can mean that something is not the thing or person in question.
KO: 항상 그런 것은 아니다.
EN: That is not always the case.

"안타깝게도 항상 그런 것은 아니다"

Unfortunately, that's not always the case.

— 특전 U보트 (1981)